1. Field of the Invention
The present invention relates generally to drainage systems located on the bottom or along the side of a swimming pool or spa. More particularly, the invention relates to a method and apparatus for preventing the entrapment of a person in the drain of a swimming pool or spa.
2. Description of the Related Art
Swimming pools and spas typically have systems for draining and recirculating water. Such systems usually have a main drain or sump located at or near the bottom of the swimming pool or spa. Water is normally suctioned out of the swimming pool or spa through the main drain, into an inlet of a suction pump, and then drained or recirculated back into the swimming pool or spa through jets located around the interior wall of the swimming pool or spa.
When bathers place their heads or bodies in the vicinity of an active drain, their hair or a portion of their body may become entrapped in a portion of the drain, such as a cover or grating. A sealed drain can develop a strong vacuum within a few seconds. If the vacuum pressure is strong enough, a bather who is entrapped by a drain may not be able to break free of the vacuum and may ultimately drown.
Swimming pool and spa safety organizations, such as the United States Consumer Product Safety Commission (CPSC), the National Spa and Pool Institute (NPSI), and various state government entities, have acknowledged the need for devices that protect against swimming pool and spa drain entrapment. Of particular concern are entrapments involving hair entanglement, limb entrapment, body entrapment, and disembowelment. Hair entanglement occurs when a bather dips below a water surface and his or her hair is sucked into and becomes entangled on a drain grate on the main drain of a swimming pool or spa. Body entrapment typically occurs when part of a bather""s torso completely covers an unprotected or damaged drain, thereby creating a vacuum within the drain from which the bather cannot break free. Limb entrapment refers to accidents in which a bather""s arm or leg is sucked into a main drain of a swimming pool or spa. Disembowelment accidents occur where small children, usually three to six years old, sit on a drain. Injury occurs when their lower intestines are sucked out of their body through their anus.
Various devices have been used to prevent entrapment. For example, swimming pools and spa have been provided with multiple drains, as opposed to just a single drain, to prevent a vacuum from being formed when one of the drains is obstructed. A system with multiple drains has its drawbacks, however, in that it can be significantly more expensive. Additionally, multiple bathers can cover the multiple drains, permitting the creation of the hazardous vacuum which the system is designed to prevent.
Pressure detection systems have also been used to reduce the risk of entrapment. Pressure detection systems shut off a drain system when the vacuum pressure within the system reaches a critical level. Unfortunately, the complexity of such systems raises reliability concerns. Thus, a need still exists for an improved method and apparatus for preventing entrapment.
One aspect of the present invention relates to a pool drain safety cover. The cover includes a base defining at least one primary fluid aperture and a plurality of secondary fluid apertures. The cover also includes a grating extending across at least the primary fluid aperture for permitting the passage of drain water therethrough. The grating has at least an upper layer and a lower layer. The upper and lower layers are adjacent, and each is comprised of a plurality of spaced ribs for permitting the passage of fluid in a clearance space between the ribs.
Another aspect of the invention relates to a method for providing a pool drain safety cover. The method includes providing a base defining at least one primary fluid aperture and a plurality of secondary fluid apertures. The method also includes positioning across at least the primary fluid aperture a grating for permitting the passage of drain water therethrough. The grating includes at least an upper layer and a lower layer. The upper and lower layers are adjacent, and each includes a plurality of spaced ribs for permitting the passage of fluid in a clearance space between the ribs.
According to either aspect of the invention, the ribs of the upper layer can be perpendicular to the ribs of the lower layer. The spacing between the ribs can be between approximately one-eighth inch and one-sixteenth inch. The base can include a perimeter portion surrounding the primary fluid aperture, and a plurality of protrusions extending from an underside of the perimeter portion. Adjacent pairs of the plurality of protrusions can define the secondary fluid apertures. A tip portion of the protrusions can extend radially beyond the perimeter portion. The tip portion can have a smoothly contoured curved face.